The present invention relates to a laser distance-measuring device. Such a laser distance-measuring device, but without night vision capability, is on the market, for example under the names LEICA GEOVID and Leica VECTOR.
Binocular devices designed for daylight use, optionally including laser distance-measuring devices which also permit monocular or binocular observation of the night image, are designed according to the following principle. For night use, at least one of the two eyepieces is removed and is replaced in each case by an optical system which consists of a lens, a low-light-level amplifier and a special eyepiece. Such a solution accordingly has weaknesses: from the technical point of view, the removal of an eyepiece in the case of military devices is in contradiction to the required gas-tightness of the device, with the result that an expensive solution is required for achieving this gas-tightness. From the tactical point of view, it is moreover disadvantageous that the user on the one hand has to carry the xe2x80x9cnight vision accessoryxe2x80x9d with him and, on the other hand, has to carefully look after the replaced standard eyepiece, which entails both weight problems and problems with respect to comfort of wearing, quite apart from the greater possibility that optical surfaces may be scratched.
In addition, the device with the night vision accessory is substantially longer and as such is more inconvenient.
Accordingly, it is the object of the invention to provide night vision capability for devices designed per se just for daylight use, such as telescopes or laser distance-measuring devices, without the above-mentioned disadvantages being present.
This object is achieved by realizing the characterizing features of claim 1. Advantageous and alternative embodiments are described by the features of the dependent claims.
Since, according to the invention, the low-light-level amplifier is permanently installed and its optional switching on makes it possible to perform functions such as, in particular, the distance measurement function also under night-time conditions without optical components, such as the eyepiece, having to be removed, the problem of possible gas permeability is eliminated. The user need no longer carry separate parts (which can thus be lost) with him, with the result that both the total weight and the comfort of wear are substantially improved. Moreover, on the basis of the present invention, the length and the ease of operation of the device having night vision capability also remain unchanged in comparison with pure daylight devices.
When a splitter mirror which can be switched on and off is referred to in connection with this invention, this is understood as meaning, in the widest sense, as including, for example, a correspondingly electrically switchable liquid crystal. However, it is preferable if at least one of the splitter mirrors is an optical element, in particular a plane-parallel plate, which can be tilted about an axis of rotation from one, optionally adjustable end position into another, optionally adjustable end position.
When a receptor is referred to in connection with this invention, this will generally be the human eye but might also be a video camera or another sensor.
Furthermore, of course, the invention can also be applied in principle to monocular devices, such as telescopes or laser distance-measuring devices; in general, however, it will be preferablexe2x80x94similarly for reasons of comfortxe2x80x94that the first and the second optical channels are part of a binocular system.